1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method and a memory medium therefor.
2. Related Background Art
In the image processing software, for selectively extracting a specified concerned area from an image, there is conventionally known a method of entering a range tolerable as color difference (tolerable color difference) by input means such as a keyboard, then designating a position in the image by position designation means, memorizing the color given by the pixel value corresponding to the designated position (designated position pixel color) and selecting, as a concerned area, a group of area constituted by pixels of which pixel values within the predetermined color difference from the pixel color of the designated position.
Referring to Tani, Uchida and Tsuji, xe2x80x9cUtilization of color information for recognition of a three-dimensional objectxe2x80x9d, Technical Report of Electronic Technology Institute, Vol. 35, pp. 308-315 (1971), employing for example chromaticity (r, g, b) for representing a color, the color difference between two colors C1 (r1, g1, b1) and C2 (r2, g2, b2) can be represented by a vector distance d. The distance d can be calculated for example by one of the following three equations:
color difference=[(r1xe2x88x92r2)2+(g1xe2x88x92g2)2+(b1xe2x88x92b2)2]xe2x80x83xe2x80x83(1)
color difference=|r1xe2x88x92r2|+|g1xe2x88x92g2|+|b1xe2x88x92b2|xe2x80x83xe2x80x83(2)
color difference=maxc3x97{|r1xe2x88x92r2|,|g1xe2x88x92g2|,|b1xe2x88x92b2|}xe2x80x83xe2x80x83(3)
In the following there will be explained the configuration and function of a concerned area extracting device realized in the representative conventional image processing software.
In the conventional concerned area extracting device, an original image constituting the target image for extracting the concerned area is stored in original image data storage means, and is displayed in image display means. In extracting an object in which the user is concerned from the image displayed on the image display means, the user enters a tolerable color difference that is necessary and sufficient for including the concerned area from the keyboard or sets a numerical value therefor. Then the user designates an arbitrary point in the concerned area with a position designating device such as a mouse, whereby the color of the concerned area is designated.
Then the color difference is calculated by comparing the color of each pixel within the image with that of the pixel at the designated position, and there are extracted pixels for which the calculated color difference is within the tolerable range. The extracted pixels are stored, as candidates of the pixels of the concerned area, in a predetermined memory device. From these candidates, there is extracted a group of pixels including the pixel of the previously designated position and the pixels adjacent thereto in succession. Thus extracted pixel group is determined as the concerned area and is displayed.
In such conventional configuration, since the user enters the range tolerable as the color difference (tolerable color difference) by the keyboard or the like and designates a pixel position contained in the concerned area on the image, the user has to estimate the tolerable color difference suitable for extracting the exact concerned area, prior to the designation of the pixel position. A failure in such estimation of the tolerable color difference may result in a failure in the extraction, such as extraction of an area far larger than the anticipated concerned area or an area only constituting a part of the anticipated concerned area. Such estimation of the tolerable color difference is difficult for the user who is unaccustomed with the image processing.
Also, if failing to extract the concerned area, the user has to repeat the cumbersome procedure of estimating and resetting the tolerable color difference and designating the pixel position.
In consideration of the foregoing, the object of the present invention is to provide an image processing apparatus, an image processing method and a memory medium therefor allowing to exactly extract the area in which the user is concerned by a simpler procedure.
The above-mentioned object can be attained, according to a preferred embodiment of the present invention, by an image processing method comprising:
a designation step of designating a position on an image;
a setting step of setting a color of a predetermined amount for the color of the position;
an area extracting step of extracting an area consisting of pixels of the color of the predetermined amount and adjacent to the position;
an extraction state display step of displaying the extraction state of the area extraction step in a distinguishable manner on a display unit; and
a control step of repeating the area extracting step by varying the color of the predetermined amount according to the input of the operator.
Another object of the present invention is to provide a novel technology in the area extracting process.